1. Field of the Invention
This invention relates to improved skin-protecting betaines and to improved cosmetic formulations, such as cleansing and bathing formulations, obtained therewith.
2. Description of the Prior Art
U.S. Pat. No. 3,225,074 shows compounds (betaines) of formula ##STR1## wherein R.sub.1 represents long-chain aliphatic hydrocarbon radicals containing from 10-20 carbon atoms, cycloalkyl, aryl, aralkyl, or alkaryl radicals; M represents a bivalent radical such as --C(.dbd.A)--D--, --B--C(.dbd.A)-- or --B--C(.dbd.A)--D-- in which C is carbon and A, B and D are oxygen, sulfur and imino; R.sub.2 is an alkylene radical (--C.sub.m H.sub.2m --) containing from 1 to 24 carbon atoms and preferably 1-12 carbon atoms; R.sub.3 and R.sub.4 may represent R.sub.5 --M--R.sub.2 -- where R.sub.5 is selected from the group consisting of R.sub.1 and short-chain aliphatic hydrocarbon radicals, i.e., alkyl and alkenyl, hydroxyalkyl EQU --(C.sub.2 H.sub.x R'.sub.4-x O).sub.y H
or --R.sub.6 --COOMe where x is a whole number from 2 to 4, y is a number from 1 to about 100, R' is methyl, ethyl, tolyl or phenyl, and Me is hydrogen, ammonium or a metal, particularly an alkali metal or an alkaline earth metal; and R.sub.6 is an alkylene radical (--C.sub.m H.sub.2m --) containing from 1 to 12 carbon atoms, and preferably 1 to 6 carbon atoms.
From German Patent No. 11 72 802 a bathing additive is known which comprises a surface active compound of the formula ##STR2## in which R.sub.1 is an alkyl radical of a fatty acid with 10 to 18 carbon atoms, R.sub.2 and R.sub.3 are the same or different alkyl or hydroxyalkyl radicals with 1 to 4 carbon atoms, x=2 or 3 and y=1, 2, 3, or 4. Compounds of the aforementioned type are recommended as germicidical shampoos. Their non-toxicity on the skin and their unusual low irritation of the eye are particularly recommended. It has been observed, however, that with commercial compounds of this type, such as where R.sub.1 is a radical derived from a C.sub.12-18 fatty acid, R.sub.2 and R.sub.3 are methyl, x=3 and y=1, eye compatibility is less than desirable.